Erzurum Province (Armenian:Էրզրում նահանգ, Կարին - Karin) is a province of Turkey, in the Eastern Anatolia Region of the country. It is bordered by the provinces of Kars and Ağrı to the east, Muş and Bingöl to the south, Erzincan and Bayburt to the west, Rize and Artvin to the north and Ardahan to the northeast. The provincial capital is Erzurum.
Known as Karanitis), Arzen, Erzen, and Karin most of the province was incorporated into the Roman Empire in the 4th century, and a small mountain city called Carana) was fortified. It became an important border fortress. This city was later (A.D. 416) renamed to Theodosiopolis, in honour of Emperor Theodosius I. Standing on the crossroads of main trade routes in Asia Minor, the area was a centre of importance for Greeks, amongst whom also lived a population of Syriac Christians, Jews, Armenians, and Assyrians. Persians and Arabs frequently clashed with the Byzantine Empire. The city (present day Erzurum) was also part of the Armenian kingdom of Tayk in the 10th century. Threatened and later devastated and looted by the Seljuk Turks in 1049, the old city of Erzen was conquered, but Theodosiopolis survived the invasion. The ruling dynasty of the time was that of the Saltukids.
Theodosiopolis repelled many attacks and military campaigns by the Seljuks and Georgians (the latter knew the city as Karnu-Kalaki) until 1201 when the city and the province was conquered by the Seljuk sultan Süleiman II of Rüm. Erzen-Erzurum fell to the Mongol siege in 1242, and the city was looted and devastated. After the fall of the Seljuk Sultanate of Anatolia (Rüm) in early 14th century, it became an administrative province of the Ilkhanates, and after their fall, became part of the Çoban beylik, Black Sheep Turkmen, Mongols led by Timur Lenk and White Sheep Turkmen. Finally, in 1514, the region was conquered by the Ottoman Sultan Suleiman the Magnificent.
During the Ottoman reign, the city served as the main base of Ottoman military power in the region. Early in 17th century, the province was threatened by Iran and a revolt by the province governor Abaza Mehmed Pasha. This revolt was combined with Jelali Revolts (the uprising of the provincial musketeers called the Celali), backed by Iran and lasted until 1628.
The city was conquered by the Russian army in 1829, given back to the Ottoman Empire with the Treaty of Adrianople (Edirne). The poet Alexander Pushkin accompanied the Russian commander-in-chief, Ivan Paskevich, during that expedition and penned a brief account of the campaign. The city was again assaulted by the Russian army in the last Russo-Turkish War in 1877.
The province was the site of the major fighting during Caucasus Campaign of World War I between Russian and Ottoman forces including the key confrontation of the campaign, Battle of Erzurum which resulted in capture of Erzurum by Russian army under command of Grand Duke Nicholas on February 16, 1916. It was returned to the Ottomans with the Treaty of Brest-Litovsk in 1918. Erzurum was also a main Turkish base during the Turkish War of Independence. It was declared a province of Turkey in 1924.